The data shows the results of the women's marathon at the 2008 Olympics, for all competitors who finished the race.
Time ( t min)
Frequency
146≤t<148
8
148≤t<150
3
150≤t<152
9
152≤t<154
11
154≤t<156
12
156≤t<158
7
158≤t<160
5
160≤t<168
8
168≤t<176
6
a. Add a cumulative frequency column to the table.
b. Represent the data on a cumulative frequency graph.
c. Use your graph to estimate the: median finishing time
d. Use your graph to estimate the: number of competitors who finished in less than 155 minutes
e. Use your graph to estimate the: percentage of competitors who took more than 159 minutes to finish
f. Use your graph to estimate the: time taken by a competitor who finished in the top 20% of runners completing the marathon.